The present invention is in the field of laser welding. More particularly, the present invention relates to a method and system for laser welding catalytic converter components or other automotive exhaust components. The present invention is also generally applicable for the laser welding of non-circular or non-concentric parts to produce consistent quality welds.
The catalytic converter, an exhaust emissions control device mandated on all cars built in the United States and many other countries, is generally designed in several common configurations. One example of a catalytic converter, referred to as a xe2x80x9cstuffedxe2x80x9d converter, comprises a cylindrical center shell that is fabricated of metal (e.g., stainless steel). The shell is filled with a layer of specialized insulation surrounding a filter medium of some type, frequently ceramic brick. A metal cap or xe2x80x9cconexe2x80x9d is positioned on each end of the shell and is held in place using a welding process. When a conventional welding process, such as metal inert gas (MIG) or tungsten inert gas (TIG) is used to create a fillet or a butt weld, the cones must be machined with very strict height tolerances, and must be positioned with great precision relative to the shell, to ensure proper alignment and fit with the shell. The MIG welding process also tends to generate a substantial amount of heat, which often causes significant material distortion of the cones and/or shell, and consequently, low quality welds. Unfortunately, this results in increased manufacturing and assembly costs, and decreased manufacturing throughput.
The present invention provides a method and system for laser welding non-circular or non-concentric parts, such as catalytic converter components.
Generally, the present invention provides a method (and corresponding system for carrying out the method), comprising:
providing a part having sections to be welded together;
rotating the part on a constant speed rotary;
generating a laser beam;
directing the laser beam onto a surface of the part to weld the sections of the part together; and
controlling the laser beam such that an angle of incidence of the laser beam on the surface of the part remains constant, the laser beam remains in focus on the surface of the part, and the laser beam moves at a constant surface speed along the surface of the part as the part is rotated on the constant speed rotary.